1. Field of the Invention
This invention relates to a cassette adapter, an adapter main body locking apparatus and a seating sensor mechanism, and more particularly to a cassette adapter for making it possible for a load port ready for a 1st cassette which accommodates a wafer of 300 mm to receive thereon a 2nd cassette which accommodates another wafer of 200 mm. It is to be noted that, in the description herein, a “wafer of 300 mm” and a “wafer of 200 mm” signify circular wafers of a diameter of 300 mm and another diameter of 200 mm, respectively.
2. Description of the Related Art
In order to perform carrying a wafer into and out of a processing tool principally for processing a wafer of 300 mm, a load port for setting a 1st cassette which accommodates a plurality of wafers therein is attached to each of places on the outer side of the processing tool at which such carrying in and out of a wafer is performed.
In a processing tool principally for processing a wafer of 300 mm in this manner, it sometimes becomes necessary to perform processing of a wafer of 200 mm. In such an instance, there is no problem if each load port itself used on the outer side of the processing tool is replaced with a load port ready for the 2nd cassette which accommodates wafers of 200 mm. However, according to this countermeasure, in order to perform processing for wafers of 200 mm which are used less frequently than wafers of 300 mm, it is necessary to manufacture and prepare a large number of load ports for exclusive use ready for the 2nd cassette and replace the load ports themselves.
Further, according to the countermeasure described above, not only manufacture of load ports for exclusive use for the 2nd cassette which is used less frequently, but also an operation for the replacement of the load ports are required. This is very uneconomical, and also the processing efficiency of wafers is deteriorated by the replacement of the load ports.
Therefore, the inventor of the invention of the present patent application has perceived an idea of use of a cassette adapter for making it possible for a load port ready for a 1st cassette which can accommodate a wafer of 300 mm to receive thereon a 2nd cassette which accommodates another wafer of 200 mm. According to the idea, the cassette adapter is fixed firmly to a carrier table of a load port for a 1st cassette which accommodates a wafer of 300 mm. Besides, the entire 2nd cassette is accommodated in a cassette cover fixed to the carrier table, and an opening on this side of the cassette cover is covered with a plate member which configures the cassette adapter. Therefore, it is necessary to lock, during an operation of carrying a wafer into and out of a processing tool, the entire cassette adapter including the plate member which closes up the opening on this side of the cassette cover in which the 2nd cassette is accommodated to the carrier table.
Further, where the cassette adapter described above is applied, it is necessary to adopt a seating sensor mechanism for detecting both of a disposition position of an adapter main body supported for pivotal motion around a pivot shaft with respect to an adapter base which configures the cassette adapter and a seating position of the 2nd cassette on the adapter main body without modifying the load port side significantly.
It is to be noted that, in the concerned technical field, a 1st cassette which can accommodate a 1st wafer of 300 mm is called FOUP (Front Open Unified Pod), and a 2nd cassette which can accommodate a 2nd wafer of 200 mm is called open cassette.
Related apparatus are disclosed in Japanese Patent No. 4388505 and JP-T-2003-504887. However, the former related apparatus essentially requires an air cylinder for exclusive use for locking and opening and closing operations of a door itself while the latter related apparatus essentially requires use of a finger for preventing a cover from opening. Further, both related apparatus have a common problem that not a standard load port but a load port for exclusive use is required.